It is known that the addition of a low concentration solution of various polymers or polyelectrolytes to sewage or wastewater effluent, for example, will promote floc formation of unwanted particulate matter suspended therein. The solutions are also useful in the centrifugation of alum muds; in the gravity settling of steel mill scale, waste pickle liquor, rolling mill wastes, as well as zinc, chromate, latex, and sugar mill wastes and tannery wastewater; in brine clarification for recovering magnesium compounds from seawater; in the clarification of beet and sugar cane juice; in sludge conditioning; as filtration aids, and like.
When particulate polymers are exposed to air containing moisture, many become sticky and form lumps quite rapidly. When exposed to water, the polymers become gummy and are difficult to dissolve or handle. Further, unless the polymer is maintained in a finely divided state when it comes into contact with the water, lumps and globular fish-eyes form which clog the feedpump, feedlines, and related apparatus of the system used in producing aged batches of polymer solution.
Additionally, polymeric powders are dusty and readily adhere to moist surfaces resulting in a build-up of semi-solid material thereon, to thereby render the wetting apparatus considerably less effective as well as requiring the apparatus to be subjected to frequent shut-down and clean-out.
The present invention provides a jet spray polymer powder wetter which permits the powder to fall into an open-ended tubular flexible insert member which is caused to extend centrally through the opening of an annularly shaped nozzle holder. The insert member has a smaller diameter than the opening and hence an annular space exists around the insert. A plurality of spaced jet spray nozzles are secured to a bottom face of the nozzle holder. The nozzles communicate with an annular passageway provided in the nozzle holder. Thus, water under pressure, supplied to the passageway, causes each nozzle to issue a high velocity jet spray therefrom. The sprays from the nozzles are directed inwardly and outwardly in alternating relationship. The inwardly directed sprays form a turbulent curtain of water which bombard the powder falling thereinto for complete wetting thereof. The outwardly directed sprays impinge against the inner wall of a spray confining cylindrical shield to constantly wash down its walls of any polymer which might be clinging thereto or attempting to build up thereon. The shield confines the sprays therewithin and leads down to a conventional aging tank.
The jet sprays induce a downward airstream in the space created in the central opening between the insert and nozzle holder which airstream aids in drawing the powder through the flexible insert as well as helping to maintain the falling powder in a finely divided state.
The apparatus of the present invention enables the wetting and mixing of the polymer powders to be accomplished in a dust-free environment and provides no moist solid surfaces to or upon which the powder can cling, thus effectively preventing any build-up of sticky material to clog vulnerable components of the system.